Illustrative transfer mediums for lift-off correction not involving radiation hardening are disclosed in U.S. Pat. Nos. 3,825,470 to Elbert et al and 3,825,437 to Blair. The disclosures of these patents recognize the requirement that the ink material of the transfer medium for lift-off correction by an adhesive be coherent as printed and be cohesive to itself in preference to the paper printed upon during the lift-off step. The disclosures of these patents show formulations which include mineral oil. The formulas of these patents are applied as a solvent solution and the solvent is then expelled to achieve hardening.
Radiation hardening of polymerizable polymers to form laminations is known in the art in various forms. Illustrative of such state of the art is the U.S. Pat. No. 2,907,675 to Gaylord, issued in 1959. The radiation in the Gaylord is an electron beam. The use of radiation hardening to form a transfer medium, specifically an electron beam, is shown in U.S. Pat. No. 3,754,966 to Newman et al. In that patent, the ink composition is a liquid mixture including mineral oil and certain polymerizable acrylates, none of those acrylates being the acrylic acrylate employed in the invention described here.
An inherent and well recognized advantage of radiation hardening to obtain a final product is that no materials are expelled from the product which might find their way into the atmosphere and act as a pollutant. In a solvent-applied process, for example, solvent must be recovered to prevent it from going into the atmosphere and such recovery may be imperfect even when the most advanced and expensive recovery equipment is employed. The foregoing and other prior art known does not encompass a lift-off correctable transfer medium made by radiation hardening.
Acrylic acrylate has recently become available for purchase and is known as a low cohesive strength material which polymerizes to a solid.
The specific embodiment of this invention includes perfluoroethylene powder to facilitate release during printing in a character image. Such a use is disclosed generally in an IBM Technical Disclosure Bulletin article entitled "Thermal Ink Transfer Aid," by C. W. Anderson and H. T. Findlay, Vol. 23, No. 12, May 1981, at page 5463.